Multiple function testing device for internal combustion engine

ABSTRACT

A multiple function device has three circuits with a common control. One circuit is an oscillator which charges a condenser that is discharged through a gaseous discharge lamp by the sparking of a spark plug to give a stroboscopic timing light; one circuit is an ohmmeter which averages the values of voltage for dwell time and open circuit time to give percentage of cam dwell; and another circuit is an averaging meter which provides a voltage that is proportional to the number of times that the breaker points open. In the latter two instances the meter is calibrated with scales that read dwell time and R.P.M. directly.

United States Colette atent 1 MULTIPLE FUNCTION TESTING DEVICE FORINTERNAL COMBUSTION ENGINE [451 Sept. 19, 1972 OTHER PUBLICATIONS v D.H. Sweet Simplet Tachometer/Dwellmeter Radio Electronics August, 1966pp. 44 & 45

Primary Examiner-Michael J. Lynch Attorney-Silverrnan & Cass [57]ABSTRACT A multiple function device has three circuits with a commoncontrol. One circuit is an oscillator which charges a condenser that isdischarged through a gaseous discharge lamp by the sparking of a sparkplug to 52 us. Cl. ..324/l6 R, 324/169 give a min! light; circuit is 51Int. Cl ..F02p 17/00 meter which averages the values "wage dwell 58Field of Search ..324/l6 T 16 R 169 15- time and circuit time givePmemage cam 315/241 R 241 S 268, 276;340f268; dwell; and another circuitis an averaging meter which 73/116 1l8 pro ndes a voltage that lsproportional to the number of times that the breaker polnts open. In thelatter two instances the meter is calibrated with scales that read [56]CM dwell time and R.P.M. directly.

UNITED STATES PATENTS 10 C] i 1 Drawing 2,908,859 10/1959 Moehring..324/16 T 3,042,835 7/1962 Badger ..324/16 T 3,573,609 4/1971 Vaher..324/16T POS S9QTT OR DISTRIB. l2

DI 71 X 30 =3 1 TO l4 NEG. BATT. BLACK R6 SJAORK W 40 PLUG RED HVMULTIPLE FUNCTION TESTING DEVICE FOR INTERNAL COMBUSTION ENGINE FIELDAND BACKGROUND OF THE INVENTION The invention relates to devices whichare used for testing internal combustion engines. The primary functionswhich are capable of being executed by the device of the invention areto operate as a timing light, as a tachometer and as a cam-dwell anglemeter.

The primary quality of the invention is its simplicity and its totallyfool-proof character.

Former devices which performed the functions of the invention werelarge, cumbersome and expensive. Many had dials to adjust, batteries tobe connected, computations to make. The instant invention isprecalibrated and has no adjustments to be made once the device has beenset up.

Through the use of this device it is possible to locate worn bushings,plates, shafts and bearings. It permits carburetors to be set up formaximum efficiency whether points are corroded or pitted. It indicatesthe correct settings for external adjustment type distributors. Itlocates defiective spark plugs. It permits setting of engines to correctR.P.M. for different conditions. It is a valuable aid for enginetune-ups and precise timing.

SUMMARY OF THE INVENTION In a single case there is provided a timinglight, tachometer and cam-dwell angle meter. A single switch controlsthe setting of the device to any one of three circuits. One circuitincludes an oscillator which charges a storage condenser that isdischarged through a gaseous discharge lamp by the sparking of a sparkplug to' give a brilliant light for use in timing. One circuit is anohmmeter which responds to the time of dwell and open time of thebreaker points of a distributor thereby giving a percentage of dwelltime. The meter of the circuit is calibrated to read zero for opencircuit and full scale when the points are closed. A third circuit is anaveraging meter which responds proportionally to the number of timesthat the breaker points open or close to give an average valueproportional to R.P.M.

BRIEF DESCRIPTION OF THEDRAWING The single FIGURE is a circuit diagramof an instrument which is constructed according to the invention and allcontained within a single case.

DESCRIPTION OF THE PREFERRED EMBODIMENT The circuit diagram illustratesthe testing device of the invention which is designated generally by thereference numeral 10. Three electrical leads are provided, these beingthe leads 12, 14 and 16 suitably colored for identification as indicatedin the diagram. The lead 12 is adapted to be connected to the positivebattery terminal of the internal combustion engine being tested or tothe primary terminal of the distributor; the lead 14 is adapted to beconnected to the negative terminal of the battery; and the lead 16 is ahigh tension lead adapted to be connected to a spark plug wire,typically that of spark plug number one. Between the leads l2 and 14there is connected a zener diode D1 in series with the resistor R1. Thelead 12 also extends to the arm of the three-way switch SW1. This switchSW1 is adapted tobe manually moved in any one of three positions,depending upon the use to which the instrument is being put.

The terminal 18 is used when the instrument 10 will be employed as atiming light; the terminal 20 is used when the instrument 10 is beingemployed as a camdwell angle meter; and the terminal 22 is used when theinstrument 10 is being used as a tachometer.

' Considering first the terminal 22, this terminal connects through acapacitor C2 and series resistor R3 to the lead 24 which is the positiveterminal 26 of the ammeter M. A capacitor C1 is connected from thepositive terminal 26 across the meter M to the negative terminal 28. Avariable resistor R2 is also connected across the meter M. The diodes D2and D3 are connected from the respective terminals 26 and 28 to thepoint 30 between the zener diode D1 and the resistor R1. They are poledas shown in the diagram.

Considering next the terminal 20, this terminal is connected by the lead32 to the variable resistor R4 and through the wiper of that resistor tothe lead 24.

Considering finally the terminal 18, this terminal connects to the lead34 through a series resistor R5 and the momentary contact switch SW2 tothe primary winding P of the transformer T1. The primary winding 1 Pconnects through the emitter-collector electrodes of the transistor O1to the lead 14. The secondary winding S of the transformer T1 isconnected at its bottom end to the base of the transistor Q1, its topend being con nected to the lead 36. The lead 36 is connected in serieswith the diode D4 to one terminal of the xenon gaseous discharge lamp X,the other terminal of the lamp X being connected to the lead 14. Thecapacitor C3 is connected across the leads 36 and 14, while thecapacitor C4 is connected across the terminals of the xenon lamp X. Anexternal capacitively coupled electrode 38 for aiding in the ignition ofthe lamp X is connected by the lead 40 through the series resistor R6 tothe lead 16.

When it is desired to utilize the instrument 10 as a timing light, thexenon lamp is flashed synchronously with one of the spark plugs. Thisstroboscopic light is then directed against the timing marks of theflywheel or the harmonic balancer, dependingupon the kind of internalcombustion engine that is being tested. The distributor locking screw isloosened and the distributor can be rotated manually until the positionof the timing marks is in accordance with the manufacturersspecification, or as desired. At this point the distributor is locked inplace.

The circuit which is used for this activity is that which is put intoplay by turning the arm of the switch SW1 to the terminal 18 anddepressing the momentary contact switch SW2. The resistor R5 functionsas a current limiting resistor. The transformer T1 and the transistor Q1together form an oscillator together with the capacitor C3 to provide asignal for charging up the storage capacitor C4. In the practicalcircuit, the transfonner T1 was an economical radio loudspeaker outputtransformer reversed so that its original output winding was the primarywinding P and its original input winding was the secondary winding S.The connection to the transistor ()1 enables the transistor to switchthe cur rent on and off in the primary winding P giving the desiredoscillation. The constants of the circuit were chosen to provide afrequency of about 1,500 hertz. The excitation for the transistor O1 isderived from the secondary winding S which is connected to the base withphasing such that the currents are in opposition. The capacitor C3provides a low impedance return path for the 1,500 hertz oscillatorysignal.

The signal produced by the oscillator is rectified by the diode D4 andcharges up the condenser C4 to a high voltage, say of the order of 300to 400 volts, which is just insufficient to ionize the xenon lamp X. Theconnections of the circuit are made with the lead 12 connected to thepositive terminal of the battery, the lead 14 is connected to thenegative terminal of the battery, while the lead 16 is connected to aspark plug wire. Under these conditions, each time that the spark plugfires, there will be a high voltage field produced between the electrode38 and the lamp X, which together with the voltage already existing dueto the charge on the capacitor C4 is sufficient to discharge the lamp X.At this point, thecharge on the condenser C4 is dumped into the lampresulting in a high intensity gaseous discharge. The resistor R6 inseries with the lead 16 provides a voltage divider action actingtogether with the distributed capacity of the lead. This reduces thesteepness of the spark plug pulse to prevent arc-over and to reduce theinsulation requirements of the leads l6 and 40.

When it is desired to use the instrument 10 as a tachometer or acam-dwell angle testing meter, the high tension lead 16 is not used. Thelead 12 is connected to the point side of the primary of the distributorand the lead 14 is connected to the negative side of the battery or toground.

When used for dwell angle testing, the arm of the switch SW1 isconnected to the terminal 20, and effectively connects the resistor R4in series with the meter M and the resistor R1. The resistor R1 hasvoltage developed in it which is limited by the zener diode D1 so thatin effect there is an ohmmeter circuit. When the points of thedistributor are open, the voltage is zero, and when the points areclosed, the voltage is maximum. The meter M is adjusted to read fullscale for the condition of the points being open by adjusting theresistor R4. The resistor R2 is a shunt to compensate for the type ofmeter used. With the points opening and closing, the meter M will assumean intermediate position which is a function of the percentage of timethat the points are closed, which in effect is the dwell time. The meterhas a scale which is calibrated to give this time, and the adjustmentcan be made to change it simply by adjusting the breaker points. I

In the case that the instrument 10 is used as a tachometer, theconnections of the leads l2, l4 and 16 are the same as when it is usedto measure dwell time. The arm of the switchSWl is now engaged with theterminal 22. Under these conditions, the resistor R3 and condenser C2 inseries with the meter M function as a differentiator, to generate aseries of pulses of substantially fixed amplitude and-width, dependingupon the time constant of the RC combination. These pulses are positiveand negative, occurring when the points open and close. The negativesignals are eliminated by the arrangement of the diodes D2 and D3 andthe positive pulses are integrated by the high capacitance capacitor Clwhich is across the meter M. This produces an average d.c. value whichis read by the meter. The greater the number of pulses, the higher thecurrent measured by the meter. The meter is thus calibrated in terms ofR.P.M. with different scales for the different number of cylinders.

Some typical values for a practical circuit are as follows:

R1 330 ohms R2 10K ohms for a meter having 1,000 ohms resistance.

1K ohms for a meter having ohms resistance.

R3 180 ohms R4 10K ohms R5 1.6 ohms Cl microfarads C2 l microfarad C30.01 microfarad C4 2.2 microfarads The zener diode had a break-downvoltage of 8.2 volts.

The instrument 10 is versatile in that many tests of an internalcombustion engine can be made using the three combined circuits forobtaining the desired information.

What is desired to secure by Letters Patent of the United States is: i

1. Apparatus for testing an internal combustion engine by measuringdistributor timing, cam dwell and R.P.M., said apparatus comprising: acam dwell measuring means and a tachometer means, both said means eachhaving an input terminal for connection to the distributor of theengine, an output terminal for connection to the engine ground, a singlemeter circuit means connected between both said cam dwell measuringmeans and said tachometer means and said output terminal said camdwelling measuring means including first circuit means connected to saidmeter circuit means to supply thereto a signal proportional to thepercentage of time that the engine breaker points are open circuit; saidtachometer means including second circuit means connected to said metercircuit means to supply thereto a signal proportional to the number oftimes that the braker points open per unit time; said first and secondcircuit means being connected within said apparatus to operatesubstantially independent of each other; and an engine timing lightcircuit having a first terminal for connection to the positive batteryterminal of the engine, for supplying exclusive dc. power to said timinglight circuit, a second terminal for connection to a spark plug of theengine, a lamp to be periodically ignited by said timing light circuit,first coupling means coupling said lamp across said first and outputterminals and for applying to said lamp pulsed d.c. energy of relativelyhigh frequency and of a value below the ignition point of said lamp,second coupling means, including voltage dropping means for protectionof the entire apparatus, connected to said second terminal andcapacitively coupled to said lamp for supplying pulsed energy ofsufficient magnitude in combination with the said high frequency valueto ignite said lamp in synchronism with the firing of a spark plug; atest lead for connection to one of the engine positive battery terminaland the distributor of the engine and manual switching means forsequential connection of any one of said input and first terminals tosaid test lead.

2. Apparatus according to claim 1 in which said first coupling means ofsaid timing light circuit includes an oscillator consisting of atransformer with primary and secondary windings and an electronic switchconnected to both windings and turned on and off by pulsed d.c. signalsfrom said secondary winding.

3. Apparatus according to claim 2 in which said electronic switchconsists of a transistor having its base connected to one end of saidsecondary winding and its emitter connected to one end of said primarywinding.

4. Apparatus according to claim 1 in which said first circuit means ofsaid cam dwell measuring means comprises resistive means in seriesbetween said input terminal and one side of said meter circuit means,and there further is provided voltage regulator means connected betweensaid test lead and said output terminals.

5. Apparatus according to claim 4 in which said second circuit means ofsaid tachometer means comprises a differentiating circuit connected tosaid input terminal and an integrating circuit connected to said metercircuit means and responsive to the output from said differentiatingcircuit.

6. Apparatus according to claim 5 in which said first coupling means ofsaid timing light circuit includes an oscillator consisting of atransformer with primary and secondary windings and an electronic switchconnected to both windings and turned on and off by pulsed d.c. signalsfrom said secondary winding.

7. Apparatus according to claim 6 in which said electronic switchconsists of a transistor having its base connected to one end of saidsecondary winding and its emitter connected to one end of said primarywinding.

8. Apparatus according to claim 1 in which said second circuit means ofsaid tachometer means comprises a differentiating circuit connected tosaid input terminal and an integrating circuit connected to said metercircuit means and responsive to the output from said differentiatingcircuit.

9. Apparatus according to claim 8 in which said first coupling means ofsaid timing light circuit includes an oscillator consisting of atransformer with primary and secondary windings and an electronic switchconnected to both windings and turned on and off by pulsed d.c. signalsfrom said secondary winding.

10. Apparatus according to claim 9 in which said first circuit means ofsaid cam dwell measuring means comprises resistive means in seriesbetween said input terminal and one side of said meter circuit means,and there further is provided voltage regulator means connected betweensaid test lead and said output terminals.

0-- c vU'NlTED STATES PATENT OFFICE CERTIFICATE CORRECTION Patent No.3,693,073 Dated September 19, 1972 Inventor(s) Michael Colette It iscertified that error appears in the ahove-identified patent and thatsaid Letters Patent arehereby corrected as shown below:

golumn 3, line 46., change "open" to -cI Losed- I Signed and sealed this11th day of June 19711.. 7

(SEAL) Attesty- EDWARD M.FLETCHER,JR. C. MARSHALL DANN Atteating OfficerCommissioner of Patents,

1. Apparatus for testing an internal combustion engine by measuringdistributor timing, cam dwell and R.P.M., said apparatus comprising: acam dwell measuring means and a tachometer means, both said means eachhaving an input terminal for connection to the distributor of theengine, an output terminal for connection to the engine ground, a singlemeter circuit means connected between both said cam dwell measuringmeans and said tachometer means and said output terminal said camdwelling measuring means including first circuit means connected to saidmeter circuit means to supply thereto a signal proportional to thepercentage of time that the engine breaker points are open circuit; saidtachometer means including second circuit means connected to said metercircuit means to supply thereto a signal proportional to the number oftimes that the braker points open per unit time; said first and secondcircuit means being connected within said apparatus to operatesubstantially independent of each other; and an engine timing lightcircuit having a first terminal for connection to the positive batteryterminal of the engine, for supplying exclusive d.c. power to saidtiming light circuit, a second terminal for connection to a spark plugof the engine, a lamp to be periodically ignited by said timing lightcircuit, first coupling means coupling said lamp across said first andoutput terminals and for applying to said lamp pulsed d.c. energy ofrelatively high frequency and of a value below the ignition point ofsaid lamp, second coupling means, including voltage dropping means forprotection of the entire apparatus, connected to said second terminaland capacitively coupled to said lamp for supplying pulsed energy ofsufficient magnitude in combination with the said high frequency valueto ignite said lamp in synchronism with the firing of a spark plug; atest lead for connection to one of the engine positive battery terminaland the distributor of the engine and manual switching means forsequential connection of any one of said input and first terminals tosaid test lead.
 2. Apparatus according to claim 1 in which said firstcoupling means of said timing light circuit includes an oscillatorconsisting of a transformer with primary and secondary windings and anelectronic switch connected to both windings and turned on and off bypulsed d.c. signals from said secondary winding.
 3. Apparatus accordingto claim 2 in which said electronic switch consists of a transistorhaving its base connected to one end of said secondary winding and itsemitter connected to one end of said primary winding.
 4. Apparatusaccording to claim 1 in which said first circuit means of said cam dwellmeasuring means comprises resistive means in series between said inputterminal and one side of said meter circuit means, and there further isprovided voltage regulator means connected between said test lead andsaid output terminals.
 5. Apparatus according to claim 4 in which saidsecond circuit means of said tachometer means comprises adifferentiating circuit connected to said input terminal and anintegrating circuit connected to said meter circuit means and responsiveto the output from said differentiating circuit.
 6. Apparatus accordingto claim 5 in which said first coupling means of said timing lightcircuit includes an oscillator consisting of a transformer with primaryand secondary windings and an electronic switch connected to bothwindings and turned on and off by pulsed d.c. signals from saidsecondary winding.
 7. Apparatus according to claim 6 in which saidelectronic switch consists of a transistor having its base conneCted toone end of said secondary winding and its emitter connected to one endof said primary winding.
 8. Apparatus according to claim 1 in which saidsecond circuit means of said tachometer means comprises adifferentiating circuit connected to said input terminal and anintegrating circuit connected to said meter circuit means and responsiveto the output from said differentiating circuit.
 9. Apparatus accordingto claim 8 in which said first coupling means of said timing lightcircuit includes an oscillator consisting of a transformer with primaryand secondary windings and an electronic switch connected to bothwindings and turned on and off by pulsed d.c. signals from saidsecondary winding.
 10. Apparatus according to claim 9 in which saidfirst circuit means of said cam dwell measuring means comprisesresistive means in series between said input terminal and one side ofsaid meter circuit means, and there further is provided voltageregulator means connected between said test lead and said outputterminals.